What is the longest running ferry boat or ship in maritime history?
I can’t say if its the longest in history, but the SS St. Mary’s Challenger has been in service for over 100 years (mostly as a cement carrier). And since ships tend to last much longer on the Great Lakes because of the fresh water, I’d think she could possibly be the longest serving overall. More info can be found on the boatnerd website http://www.boatnerd.com/pictures/fleet/stmaryschallenger.